Stage 1.0 Added appropriate documentation; removed local var from tor_global_sandbox().

- CR (fix) doxygen comments and copyright notices
- tor_global_sandbox() now returns -1/-2 on failure and 0 on success without any local variables
- CR (fix) removed comments about periodic events; these are to be discussed
Stage 1.0 CR (fix): cross platform compilation, Sandbox support warning.

- have developed an initial structuring of the code for the 3 main OS (linux, windows, mac) using ifdefs; can be extended for further subdivisions of the OSs, or different implementations;
- added a warning that in the case that the Sandbox command line parameter is set to true on a platform which is not supported (currently windows and mac)